This application claims priority from European Patent Application No. 04 024 814.8 filed Oct. 19, 2004 , hereby incorporated by reference in its entirety.
The invention relates to a glass coating.
Coatings of architectural glass serve the purpose of reflecting or absorbing certain wavelengths or wavelength ranges of daylight such, that the light entering the room through the windows differs from the light outside the room.
An important function of such coatings consists in reflecting heat radiation in order for rooms not to be heated too much in the summer and not to cool down too much in the winter. But herein the transmission of visible light should not be significantly reduced, i.e. the coating should have high transmission in the visible range and high reflection for heat or infrared radiation.
Coating systems fulfilling this function are referred to as Low-E coating systems, where “E” represents “emissivity”.
A Low-E coating system is already known, which comprises as the substrate a glass pane of mineral glass on which five individual layers are disposed one above the other (DE 42 113 63 A1). On this substrate is disposed a first layer of ZnO with a thickness of 400 Å. On this first layer is applied a second layer of Ag having a thickness of 90 Å. A third layer, disposed on the second layer, is comprised of one of the metals Ti or NiCr of a thickness of approximately 15 Å. Onto this third layer is applied a fourth layer comprised of ZnO and having a thickness of 320 Å. Onto the fourth layer, lastly, is applied a fifth layer of TiO2 with a thickness of 70 Å. The thin layer of silver is here essentially the layer reflecting the infrared light.
A further coating transparent to visible light and reflecting infrared light is disclosed in WO 95/29883. This coating is applied on a glass substrate and is also comprised of at least five layers. As the first layer on this glass substrate is applied an oxide, for example zinc oxide, tin oxide, indium oxide, etc. The second is formed by a silver film, while the third layer is a metal layer, which protects the subjacent silver layer during a sputtering process. Following it is a further metal oxide layer, which prevents the silver layer from oxidizing. The fifth and last layer is formed by a silicon nitride layer.
Further known is a thermally insulating coating system, which is suitable for curved panes (DE 198 50 023 A1=U.S. Pat. No. 6,180,247 B1). This coating system is comprised of at least one coating of a noble metal enclosed in protective layers. Such a coating system can specifically be comprised of TiO2—NiCrOx—TiO2—Ag—NiCrOx—Si3N4.
Improvement of thermal insulation has so far only been achieved by means of complicated double silver or split silver coating systems.
The object of the invention is to improve the thermal insulation of a substrate coating with high transmission of visible light without increasing the thickness of a layer reflecting heat radiation.
This object is achieved according to the characteristics of patent claim 1.
The invention relates to a glass coating and a method for the production of this glass coating. The glass coating comprises a first layer of ZnO and a second layer of Ag disposed thereon. Before the Ag layer is applied onto the ZnO layer, the latter is irradiated with ions.
The advantage achieved with the invention lies particularly therein that through a special pretreatment of that layer on which the silver layer is applied, the epitaxial growth of the layer reflecting the heat radiation is affected such, that its surface resistance is decreased by up to 20% without having to apply more material. The layer reflecting the heat radiation is here preferably silver and the layer onto which the silver is applied, is preferably ZnO. The pretreatment of this ZnO preferably is carried out by ion bombardment.
To the silver can be mixed small quantities—less than 10 percent by weight—of Cu, Al, Nd, In, Yt, Sb, V and the like. Alternatively to ZnO or ZnO:Al, for example NiCr, NiCrOx, TiOx, TiO2,W, WO, WOx, Zr, ZrOx, ZrO can be used for the epitaxial growth layer.
In a preferred embodiment, the infrared radiation-reflecting layer includes a material with a silver fraction of at least 50%.
In another preferred embodiment, the layer treated by ion irradiation contains of a material with a ZnO fraction of at least 50%.
In another embodiments, the layer treated by ion irradiation includes ZnOx or ZnO:Al or Zn:AlOx, wherein 0<×≦1.
In comparison to double silver or split silver Low-E coating systems, the invention permits faster production, since fewer individual layers and less complicated processes are required. The production is also more cost-effective since less target material and fewer cathodes are required. The coating installations can overall be laid out smaller. The simple coating system yields fewer rejects and requires less maintenance effort, lower expenditures and less consumable material. In comparison to single-silver Low-E coating systems, the products fabricated according to the invention have better functionality. In a tempered coating system the surface resistance is decreased by up to 15%. Therewith emissivities ε<0.040 are possible and specifically at a transmission above 88%.
An embodiment example of the invention is depicted in the drawing and will be described in the following in greater detail.